A metal complex having the composition Cr `(NH_(3))_(4)Cl_(2)` Br has been isolated in two forms A and B. The form A reacts with `AgNO_(3)` to give a white precipitate readily soluble in dilute aqueous ammonia whereas B gives a pale yellow precipitate soluble in concentrated ammonia.
The formula of the complex A is

Options

A. `[Cr(NH_(3))_(4)Br]Cl_(2)`
B. `[Cr(NH_(3))_(4)BrCl]Cl`
C. `[Cr(NH_(3))_(4)Cl_(2)]Br`
D. Both (a) and (b) are possible

Answer

B

Explanation

As form A is readily soluble in dilute aqueous ammonia, it must have `Cl^(-)` outside the coordination sphere, i.e., its formula is `[Cr(NH_(3))_(4)BrCl]^(+)Cl^(-)`.